U.S. patent application number 13/147457 was filed with the patent office on 2011-12-01 for thixotropic anhydrous shear thinning peroxide dispersions.
This patent application is currently assigned to Arkema Inc.. Invention is credited to Joseph M. Gravelle, Thomas H. Kozel.
Application Number | 20110291045 13/147457 |
Document ID | / |
Family ID | 42542361 |
Filed Date | 2011-12-01 |
United States Patent
Application |
20110291045 |
Kind Code |
A1 |
Gravelle; Joseph M. ; et
al. |
December 1, 2011 |
THIXOTROPIC ANHYDROUS SHEAR THINNING PEROXIDE DISPERSIONS
Abstract
Provided are dispersions which comprise more than about up to 55
percent by weight or more of an organic peroxide which is normally
solid in an anhydrous liquid phase such as dibutyl maleate or
dioctyl adipate, with about 5% by weight or more fumed silica to
provide a thixotropic, storage stable organic peroxide paste.
Addition of about 5 weight % or more of fumed silica was found to
result in the formation of a shear thinning anhydrous dispersion of
organic peroxide which was storage stable.
Inventors: |
Gravelle; Joseph M.; (Spring
City, PA) ; Kozel; Thomas H.; (Pottstown,
PA) |
Assignee: |
Arkema Inc.
King of Prussia
PA
|
Family ID: |
42542361 |
Appl. No.: |
13/147457 |
Filed: |
February 3, 2010 |
PCT Filed: |
February 3, 2010 |
PCT NO: |
PCT/US2010/022959 |
371 Date: |
August 2, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61149445 |
Feb 3, 2009 |
|
|
|
Current U.S.
Class: |
252/182.14 |
Current CPC
Class: |
B01F 17/0007 20130101;
C08F 4/34 20130101; C08K 5/14 20130101 |
Class at
Publication: |
252/182.14 |
International
Class: |
C09K 3/00 20060101
C09K003/00 |
Claims
1. An anhydrous dispersion comprising about 40% by weight or more
of an organic peroxide in an anhydrous liquid phase and 5% by
weight or more of fumed silica.
2. The anhydrous dispersion of claim 1 which is phthalate free.
3. The anhydrous dispersion of claim 1, wherein said organic
peroxide is selected from the group consisting of diacyl peroxides,
aliphatic diacyl peroxides, ketone peroxides, aldehyde peroxides,
peroxy dicarbonates, acylperoxy alkylcarbonates and mixtures
thereof.
4. The anhydrous dispersion of claim 3, wherein said diacyl
peroxides are selected from the group consisting of benzoyl
peroxide, o-methylbenzoyl peroxide, o-methoxybenzoyl peroxide,
o-ethoxy benzoyl peroxide, o-chlorobenzoyl peroxide,
2,4-dichlorobenzoyl peroxide and mixtures thereof.
5. The anhydrous dispersion of claim 3, wherein said aliphatic
diacyl peroxides are selected from the group consisting of decanoyl
peroxide, lauroyl peroxide, myristoyl peroxide and mixtures
thereof.
6. The anhydrous dispersion of claim 3, wherein said ketone
peroxides are selected from the group consisting of 1-hydroxy
cyclohexyl peroxide, 1-hydroperoxycyclohexyl peroxide and mixtures
thereof.
7. The anhydrous dispersion of claim 3, wherein said aldehyde
peroxides is 1-hydroxy heptyl peroxide.
8. The anhydrous dispersion of claim 3, wherein said peroxy
dicarbonates are selected from the group consisting of dicetyl
peroxydicarbonate, di(4-t-butylcyclohexyl) peroxydicarbonate and
mixtures thereof.
9. The anhydrous dispersion of claim 3, wherein said acylperoxy
alkylcarbonate is acetyl peroxy stearyl carbonate.
10. The anhydrous dispersion of claim 1, wherein said anhydrous
liquid phase comprises C2-C10, saturated or unsaturated diesters
made from diacids or C1 to C10 alcohols.
11. The anhydrous dispersion of claim 10, wherein said diesters
made from diacids are selected from the group consisting of dibutyl
maleate and dioctyl adipate.
12. The anhydrous dispersion of claim 1, wherein said anhydrous
dispersion comprises about 55% by weight or more of said organic
peroxide.
13. A process of imparting thixotropic properties to a phthalate
free, anhydrous organic peroxide paste comprising 40% by weight or
more of organic peroxide comprising mixing with said paste 5% by
weight or more of fumed silica.
14. The process of claim 13, wherein said organic peroxide is
selected from the group consisting of diacyl peroxides, aliphatic
diacyl peroxides, ketone peroxides, aldehyde peroxides, peroxy
dicarbonates, acylperoxy alkylcarbonates and mixtures thereof.
15. The process of claim 14, wherein said diacyl peroxides are
selected from the group consisting of benzoyl peroxide,
o-methylbenzoyl peroxide, o-methoxybenzoyl peroxide, o-ethoxy
benzoyl peroxide, o-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl
peroxide and mixtures thereof.
16. The process of claim 14, wherein said aliphatic diacyl
peroxides are selected from the group consisting of decanoyl
peroxide, lauroyl peroxide, myristoyl peroxide and mixtures
thereof.
17. The process of claim 14, wherein said ketone peroxides are
selected from the group consisting of 1-hydroxy cyclohexyl
peroxide, 1-hydroperoxycyclohexyl peroxide and mixtures
thereof.
18. The process of claim 14, wherein said aldehyde peroxides is
1-hydroxy heptyl peroxide.
19. The process of claim 14, wherein said peroxy dicarbonates are
selected from the group consisting of dicetyl peroxydicarbonate,
di(4-t-butylcyclohexyl) peroxydicarbonate and mixtures thereof.
20. The process of claim 14, wherein said acylperoxy alkylcarbonate
is acetyl peroxy stearyl carbonate.
21. The process of claim 13, wherein said anhydrous liquid phase
comprises a C2-C10, saturated or unsaturated diester made from
diacids, a C1 to C10 alcohols or mixtures thereof.
22. The process of claim 21, wherein said diester made from diacids
are selected from the group consisting of dibutyl maleate and
dioctyl adipate.
23. The process of claim 13, wherein said anhydrous dispersion
comprises about 55% by weight or more of said organic peroxide.
Description
FIELD OF INVENTION
[0001] The present invention relates to anhydrous pastes of organic
peroxides. The pastes are phthalate free and exhibit thixotropic
properties. That is, the pastes are shear thinning so as to be
pumpable/pourable when mixed or stirred which makes their handling
and use easier.
BACKGROUND
[0002] Peroxides have, as a general property, a tendency to be
flammable and explosive with some peroxides exhibiting such
properties to a greater extent than others. For example, benzoyl
peroxide may decompose when dry due to shock, friction, or static
electricity. This property carries with it the obvious hazards to
the users of these materials as well as to the manufacturers and
intermediate handlers thereof. One particularly burdensome aspect
of this property occurs during shipment of the peroxides.
Accordingly, it has long been an object to provide flame resistant
organic peroxide compositions. For example, U.S. Pat. No. 3,507,800
is directed to providing a flame resistant peroxide composition
consisting essentially of three components--water, peroxide and
solvent wherein the water is at least about 18 percent of the
composition.
[0003] The safety and end-use advantage provided by water-soluble
or water-emulsifiable peroxides is recognized. U.S. Pat. No.
3,825,509 describes a process for the suspension polymerization of
vinyl chloride wherein the initiator is an aqueous emulsion of an
organic peroxide in which the peroxide is present in an amount up
to 19 weight percent. The surfactant used to prepare the aqueous
peroxide emulsion is a combination of polyvinyl alcohol and
polyoxyethylene sorbitan monolaurate. However, emulsions containing
greater than about 19 percent by weight of organic peroxide are
described as being too viscous and therefore difficult to
handle.
[0004] There have been attempts in the past to make peroxide
dispersions. U.S. Pat. Nos. 4,039,475 and 4,092,470 disclose
stable, pumpable aqueous suspensions of organic peroxides using a
mixture of a) nonionic emulsifiers having a maximum HLB value of
12.5 and b) nonionic emulsifiers having a minimum HLB value of 12.5
or anionic emulsifiers. U.S. Pat. No. 4,734,135 discloses aqueous
suspensions of solid organic peroxides using a protective colloid,
a surface active agent and water. U.S. Pat. No. 4,440,885 teaches
emulsions of a solid organic peroxide using an emulsifier having an
HLB value from about 9 to about 20, a hydrocarbon solvent and
water.
[0005] Organic peroxides are used as initiators in polymerization
operations such as for acrylic and polyester polymerizations. The
organic peroxides such as benzoyl peroxide are commercially
available as solutions/dispersions in phthalates such as dimethyl
phthalate and dibutyl phthalate. Due to a perception of toxicity
issues with phthalates, there is a current effort to discontinue
their use in the production of polymers for certain uses.
SUMMARY OF THE INVENTION
[0006] The present invention is direct toward an anhydrous,
phthalate free, peroxide paste which exhibits thixotropic
properties. The anhydrous, phthalate free, peroxide paste of the
present invention allows for the transportation and handling of a
peroxide paste having a high concentration of peroxide which paste
is shear thinning so it can be easily pumped/poured and is also is
resistant to separation upon standing. The anhydrous, phthalate
free, peroxide paste of the present invention is a paste of organic
peroxide and fumed silica in a liquid phase. The liquid phase could
be based upon diesters made from diacids such as C2-C10, saturated
or unsaturated, and alcohols ranging from C1 to C10. It was
discovered that the addition of anhydrous fumed silica to an
anhydrous benzoyl peroxide in dibutyl maleate or dioctyl adipate
pastes resulted in an anhydrous paste which was shear thinning,
i.e. thixotropic.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0007] The anhydrous pastes of the present invention comprises an
organic peroxide, which is normally solid, in a phthalate free,
liquid phase such as dibutyl maleate or dioctyl adipate the mixture
also includes anhydrous fumed silica. By phthalate free, within the
scope of the present invention, is meant substantially free of
phthalates and that phthalates are not intentional add to the
paste. It is intended that phthalate free herein include pastes
which contain trace amounts of phthalates.
[0008] Exemplary of suitable organic peroxides are aromatic diacyl
peroxides, such as benzoyl peroxide, o-methylbenzoyl peroxide,
o-methoxybenzoyl peroxide, o-ethoxy benzoyl peroxide,
o-chlorobenzoyl peroxide and 2,4-dichlorobenzoyl peroxide;
aliphatic diacyl peroxides, such as decanoyl peroxide, lauroyl
peroxide and myristoyl peroxide; ketone peroxides, such as
1-hydroxy cyclohexyl peroxide and 1-hydroperoxycyclohexyl peroxide;
aldehyde peroxides such as 1-hydroxy heptyl peroxide; peroxy
dicarbonates such as dicetyl peroxydicarbonate,
di(4-t-butylcyclohexyl) peroxydicarbonate and acylperoxy
alkylcarbonates, such as acetyl peroxy stearyl carbonate and the
like.
[0009] The pastes of the present invention comprise about 40
percent or more by weight of organic peroxide. One of the features
of the present invention is that it enables the preparation of
pastes containing about 40 or more percent by weight of organic
peroxide which pastes are pumpable because they are shear thinning.
Heretofore it has been difficult to make pumpable pastes containing
about 40 or more percent by weight organic peroxide. In this
description, shear thinning means that viscosity drops as the shear
rate increases. Thus, the viscosity of the peroxide pastes of the
present invention will drop as the paste is stirred or mixed and it
becomes pourable or pumpable easing use.
[0010] The organic peroxide is formed into a paste in a liquid
phase such as a solvent/plasticizer such as dibutyl maleate or
dimethyl maleate. Preferably the paste comprises about 40% and more
preferably, 55% by weigh benzoyl peroxide in dibutyl maleate or
dioctyl adipate. The organic peroxide paste is mixed with fumed
silica in amounts greater than about 5% by weight to provide a
thixotropic paste. It was found that when less than 5% of fumed
silica was added to a 55 wt % benzoyl peroxide in dibutyl maleate
or dioctyl adipate paste, phase separation occurred after a few
days. However, when about 5% by weight of fumed silica was added,
an extremely viscous paste form which did not separate over time
and exhibited thixotropic properties.
[0011] The anhydrous, phthalate free peroxide paste of the present
invention is formed by simple mixing of the organic peroxide with
the liquid phase followed by addition of the fumed silica. The
fumed silica is a very light fluffy power which is preferably added
in multiple steps, typically three steps, in order to facilitate
dispersion of the fumed silica throughout the organic peroxide
paste. Upon addition of the full amount of fumed silica to the
organic peroxide paste, the paste is poured into a suitable
shipping container where it will thicken. The thickened paste can
be easily removed from the container for use by mixing or stirring
whereupon it becomes pourable.
[0012] The advantageous properties of this invention can be
observed by reference to the following examples, which illustrate
but do not limit the invention.
EXAMPLES
Example 1
[0013] A sample of paste in accordance with the present invention
was prepared by combining anhydrous benzoyl peroxide and dibutyl
maleate in a high shear mixer. After the peroxide was thoroughly
dispersed, fumed silica (AEROSIL.RTM. 972 available from Evonik)
was slowly added (typically in three portions). The final paste was
then mixed in a high shear blender for 30 to 60 seconds. The sample
was the placed in a 25.degree. C. oven overnight. The following
morning, the sample was removed from the oven and stirred
vigorously. The viscosity was measured over the following three
hours.
[0014] Paste Composition:
TABLE-US-00001 Dibutyl Maleate 45% by weight Benzoyl Peroxide 50%
by weight AEROSIL .RTM. 972 5% by weight
[0015] Apparatus: Brookfield Model DV-II+ Viscometer
[0016] Spindle: T-C @ 2 rpm (helipath used)
[0017] Temperature: 25.degree. C.
[0018] Viscosity:
TABLE-US-00002 Time Viscosity (Minutes) (cP) 0 4,500 5 55,000 10
81,500 30 124,500 60 156,000 120 212,000 180 227,000
Example 2
[0019] A sample of paste in accordance with the present invention
was prepared by combining anhydrous benzoyl peroxide and dioctyl
adipate in a high shear mixer. After the peroxide was thoroughly
dispersed, fumed silica (AEROSIL.RTM. 972 available from Evonik)
was slowly added (typically in three portions). The final paste was
then mixed in a high shear blender for 30-60 seconds. The viscosity
was measured over a two-hour period at 22.5.degree. C. (Room
Temperature).
[0020] Paste Composition:
TABLE-US-00003 Dioctyl Adipate 45% by weight Benzoyl Peroxide 50%
by weight AEROSIL .RTM. 972 5% by weight
[0021] Apparatus: Brookfield Model DV-II+ Viscometer
[0022] Spindle: T-C @ 2 rpm (helipath used)
[0023] Temperature: 22.5.degree. C.
[0024] Experimental Results:
TABLE-US-00004 Time Viscosity (Minutes) (cP) 0 2,500 5 20,000 10
31,000 30 44,500 60 56,000 120 67,000
[0025] The data in examples 1 and 2 shows that the viscosity of the
mixture increased significantly with time after the string is
stopped, i.e. the mixture was thixotropic. No phase separation was
observed over time in either example.
[0026] Having described the invention, we now claim the following
and their equivalents.
* * * * *